Im not sure whats going or why, but i get this message when using FMath::Pow(a,b)
Since you decided not to post the code where the warning is generated my guess is you wrote something like FMath::Pow(2, 3); instead of FMath::Pow(2.f, 3.f);
FMath::Pow(2, 3);
FMath::Pow(2.f, 3.f);